Tongue-and-groove concrete plank molding apparatus



April 22, 1958 v. F. LAwsoN ToNGUE-AND-GRoovE.CONCRETE PLANK MOLDINGAPPARATUS 2 sheets-sheet 1 Filed May 19. 1954 WaoHE'Lazwsw,

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pnl 22, 1958 V. F. LAWSON 2,831,232

ToNGUE-AND-GRoovE CONCRETE PLANK MOLDING APPARATUS Filed May 19, 1954 2Sheets-Sheet 2 a Viva# lwllesoz@v TONGUE-AND-GROOVE CONCRETE LANKMOLDING APPARATUS Victor F. Lawson, Winchester, Mass., assigner toLawson Manufacturing Corp., Wakecld, Mass., a corporation ofMassachusetts Application May 19, 1954, Serial No. 430,842

1 Claim. (Cl. 25-121) This invention relates to the art of molding orcasting concrete. More particularly it aims to improve 4the productionof tongue-and-groove concrete planking, through anew and improved meansfor making the same.

In the accompanying drawings illustrating one embodimentof means for thepractice -of the invention:

Fig. l is a perspective view looking down onto one end portion of acomplete molding assembly or box for forming a gang of individual planksin erect position with the long dimensions horizontal, the mold beingshown opened at the near end and with the several plank cavities emptyof concrete mix;

Fig. 2 is a cross-section through the mold of Fig. l with thetongue-forming topping bars in place upon the top edges of thelongitudinal separator plates and with the filling of the series ofplank cavities completed;

Fig. 3 is a cross-section of a tongue-and-groove concrete plank asresultant from the apparatus of the invention;

Fig. 4 shows separately a cage of reinforcement such as employed ineachplank cavity; and

Fig; 5 is a perspective view on a larger scale showing portions ofV anadjacent pair of topping bars further illustrating the manner of formingthe tongue along the top longitudinal edge face of each plank.

Precastlight-weight tongue-and-groove concrete planks are now known andextensively used in building construction. They are relatively thinmolded concrete slab elementsY adapted for laying horizontally asflooring and roofingupon metal or other supporting framework members.Theyare nailable, also can -be cut on the job with a power abrasive saw.Such concrete planking can be laid in continuity over the supports, wtihrandom end joints, and with a minimum of labor and cutting. Buildingerection is'accordingly simplified and expedited.

The individual precast concrete planks may be variously dimensioned. Acurrently accepted standard is 16 inches wide, l0 feet long and 2 inchesin thickness. The planks have uniform tongues and grooves, generally atall four sides, a tongue along one long edge and a corresponding grooveat the opposite long edge, and similarly with respect `to the end edges.The tongues and grooves usually have inclined sides, giving them atrapezoidal cross-section. The planks are usually cast in gangs in anoverall coffin-like mold divided longitudinally by spacer plates intothe selected plurality of individual plank cavities, having the longerdimension horizontal.

Heretofore considerable diiiculty has been experienced in the formationof the edge interlock element for that longitudinal edge face of theplank which is at the top in the mold. The general practice has been toform the tongue -along the bottom edge of the individual planks, intheir molding position, to fill the cavities completely and thereafterfashion a tongue-receiving groove along and in the top `surface of theilling concrete mix at each plank cavity. This has generally been donemanually and individually for each plank by running an appropriatelyformed trowel along in the concrete beforeV it sets. Anotherattempthasbeen to employ rods of general groove 2,831,232 Patented Apr. 22, 1958shape in cross-section and to force them down into the filling materialat the top of each plank mold cavity, thus again hand-treating eachplank individually. Such procedures are tedious and labor-consuming andhave proved generally unsatisfactory. The resulting planks frequentlydisplay much irregularity in the, longitudinal groove element,incomplete formation thereof and also there is objectionable wastage ofll material displaced from the groove in the manual troweling or in thecompressive formation thereofmentioned, together with a tendency fordistortion and irregularity in the formation of the entire plank.

In accordance with the presen-t invention I have devised a process .andmeans for the practice of the same, novelty employing groove formationat the longitudinal bottom edges of the planks and tongue formationalong the top edges, as--opposednto the prior procedure, and in suchfashion that the top tongues are readily and quickly formed to shape andysize with requisite certainty and accuracy, with little or no excessandwaste material, and with a minimum of labor.

=Referring-now to the drawings in'more detail, the mold equipment ormold box in general comprises a rigid iloor plate 1l which may be set'onany suitable bed or support 2. Along one side portion -of the floorplate is erected one outer side wall or plate 3, this being preferablysecured-permanently to the lloor plate 1 as by welding and beingsuitably reinforced as by one or more longitudinal stringers 4, 4 Weldedalong it. The box may be of any desired width to accommodate acorresponding number or gang of individual plank cavities, eachdesignated generally in Fig. l at 5', some ten such cavities 5 beingshown in Figs.` 1 and 2, in side-by-side relation and arranged forthe-on-edge formation of the like number of individual tongue-and-grooveplanks P such `as tha-t of Fig. 3 and as seen in the molding position inFig. 2. The opposite outer side wall 6 of the mold box may be generallysimilar to` side. plate 3 and including longitudinal reinforcement as at7, 7 but is removably'disposed with respect to the .other mold parts.

The mold further comprises a bottom form 8 set onto the bed plate 1 andof afwidth toextend across the entire mold interior either integrally-orin sections. This bottom form 8 has fashioned along it a series ofupstanding ribs 9, one disposed centrally along each plank cavity 5 andof cross-sectional shape to eifect formation of the tonguereceivinggroove g, Fig. 3, along the bottom edge of each plank P. The bottom form8 also has at its upper face a series of longitudinal notches 8adistributed in equal spaced relation and adapted to receive and positionthe lower edges of the removable longitudinal vseparator plates 1G whichdefine the individual plank cavities. The mold box further comprises endwalls one of which is seen in Fig. 1 in open position as though swungaround laterally in the manner of a door, the other end of the mold boxbeing similarly equipped., The end wall 11 carries a series of plank endgroove-forming ribs 12 of similar cross-sectionv asy thev bottom ribs 9and spaced across the end plate 1l' so as to align with the bottom ribscentrally of the respective plank cavities 5. The other mold end wall,not shown, is similar to end plate 11 but instead of ribs 1li carries aseries of similarly spaced vertical recesses for the molding ofcorrespondingly shaped tongues at that end face of each of the planks P.

The openable end walls l1 and' the removable outer side plate 6 areadapted to be securely locked in closed position upon they bed plate 1and with respect to the xed side wally 3 as byV means of removable pinsand interlocking latches of which two are seen at 13, 14 in Fig. 1, theend walls having Y appropriate external flange projections 15 aperturedto align with pin-receiving apertures in the external longitudinalstringers 4 and 7 of the mold sides. Any known or preferred form ofreleasable securer means for the mold parts may be used.

The mold equipment further comprises for each individual plank cavity 5a reinforcement cage as indicated generally at 20 in Fig. 4 showing onecage separately, portions of the several cages in the respectivecavities being seen also in Figs. l and 2 and in the iinal productposition in Fig. 3. These comprise longitudinal steel members 2ldisposed in parallelism and symmetrically spaced and arranged to alordthe desired distribution of reinforcement. The example of Fig. 4represents tiers of seven longitudinal rods 21, two tiers for each plankdisposed in horizontally paired relation. These rods are held in xedrelation by similar upright rods or chairs 22, of which seven also areshown in lateral paired relation, together with a number of transversemembers or spacers 23. All of these members are welded together, each tothose adjacent to provide a welded steel mesh cage unit which may bemanipulated as such and readily dropped into place, one in each plankcavity S of the mold. By reason of the integration of the reinforcementinto such cage unit wherein all the component parts are relatively xedit is insured that in the Iinished precast planks P the reinforcementwill be located Where it is designed to be.

It will be understood that the numbers of longitudinal members 21 andalso of the chairs 22 and spacers 23 may be varied as appropriate to thecharacter and dimension of the particular planking. The illustrativeform shown having seven pairs of the longitudinal steel and also a likenumber of the chairs 22, with spacers 23 at alternate chairs, is wellsuited to the production of planks to a standard size such as 2 inchesthick, 16 inches wide and l0 feet long. The cage parts in 4such instancemay be for example No. 7 gauge steel wire. The spacers 23 in theinstance of a 2inch thick plank, are made exactly 2- inches long, foraccurate reception between each two adjacent longitudinal plates of theplank cavitise 5, aiding to place the plates while presenting therespective reinforcement cages in proper position in the correspondingcavities.

In addition to and in cooperation with mold equipment Iso far describedand forming a part theerof, I utilize a plurality of novel toppingplates each herein designated at 30. A number of these are shown inexploded position as prior to installation at the upper left portion ofFig. l, while in Fig. 2 the appropriate number of topping bars for thegiven mold is shown in their operative use position. These topping baror top tongue-forming elements are shown separately on a larger scale inFig. 5.

Each such topping bar 39 comprises a single unitary strip or bar ofsteel, each of a length corresponding to that of the plank mold cavities5 and adapted to provide in effect top wall forms for the cavities,'theends of the topping bars being received between the opposite end walls11 of the mold box. These topping bars 30 are of a thickness, in thevertical direction with respect to the installed position of the bars,corresponding to that desired for the height of the plank tongues, oneof which is seen at t in Fig. 3 and also in Fig. 2 on the severalplanks. Each topping bar 30 has a longitudinal recess or channel 3lcentrally along its under or inner face and dimensioned to fit snugly insecure seated position upon and along the top edge of any one of thelongitudinal spacer plates 10 of the mold. Each topping bar 30 is of awidth to overlie the adjacent approximately half-width of the moldcavities 5 to each side of the spacer plate l0 on which the given bar ismounted, while leaving between each two adjacent bars 36 an open-topcavity `space centrally of each given cavity and of a width, height Aandshape to form thereon the longitudinally continuous top tongue t for thecorresponding planks P.

ln the illustrated example the tongues t, likewise the grooves g inwhich they are to tit in the use position of the planks, are of atruncate or trapezoidal cross-sectional shape. Accordingly the oppositeside faces 32, 32 of each topping bar 30 are inclined at the appropriateangle, oppositely and downwardly toward each other in the use position,that is, toward the particular separator plate 10 on which the bar is tobe installed. The bars 30 each being of uniform width throughout and ofthe approximate half-cavity width to each side of the particularsupporting plate if), less an amount equal to one-half the thickness ofthe tongue, it results that there is presented between each two adjacentbars the desired truncate or trapezoidal tongue-forming channel orelongate cavity space as indicated at 35 in Fig. 5 and in Fig. l. Itwill be evident also that in the installed or use position of Fig. 2with a topping bar 30 applied along the top edge of each spacer plate 10that the latter are aiforded substantiai additional longitudinalreinforcement and resistance against flexure, warping or likedisplacement or deformation in the course of the molding and settingoperation. The ilat under faces of the topping bars 30 define thehorizontal corner or shoulder portions for the upper longitudinal edgesof the planks in the corresponding cavities.

In the practice of the invention a mold box such as represented in Fig.l is completely set up and the removable wall parts secured in moldingposition. A reinforcement cage 20 is set into each plank cavity 5. lnthe following initial stage of the molding process the severalindividual plank cavities S are left open at the top. The appropriatenumber of topping bars 30 are made ready for installation, eleven ofthem in the illustrated example of a ten cavity mold comprising ninespacer plates 10 and the two outer side walls 3 and 6 which complete theoutermost cavities. It will be understood that said outer side walls 3and 6 may be of the same thickness as the intermediate spacer plates 10in which case the topping bars for installation upon them may be thesame in all.

resepcts as those for the spacer plates, as represented in Fig. 2. Or ifpreferred or if found more convenient the topping bars for the outsidewalls may be of reduced width upon the outside of the walls and need nothave the outermost edges inclined and likewise the underseating channelor recess 31 in the case of a side wallof a thicker dimension than thatof the spacer plate 10 will be correspondingly proportioned, and in someinstances one or both of the outermost topping bars may be xed on orformed as a part of the corresponding side wall 3 or 6.

With the mold set up, the appropriate quantity of concrete mix havingbeen prepared and made available, for example an aerated concrete usinga light-weight slag aggregate, preferably free of cinders, and with aPortland cement, such concrete mix is poured into the several cavities 5of the mold to a predetermined upper level close to but desirably justenough short of the top edge of the spacer plates and side walls so asto leave an open volume approximately corresponding to that of the toptongue to be formed at each cavity top. With the cavities thus nearlybut slightly less than lled the series of topping bars 30 are set downinto the T-like straddling position along the top edges of the separatorplates 10 and the side walls 3 and 6 and accurately seated in levelposition upon them. With the appropriate predetermined level of fillingas described this operation causes some of the'moist concrete mix at thetop of the respective cavities to be forced up into the tongue-formingchannels 35 between the paired inclined sides of the adjacent toppingbars 30. Under the use of the described appropriate quantity of concretelill, the top tongues t are accurately and substantially fully formedthroughout their major volume. Any slight excess is levelled off orcompressed into any voids and any needed quantity of the concrete mix isthen supplied along and into any minor remaining gaps or aesinet:

5 voids of the several tongues t as by the use of a pressure applicatoror otherwise.

The entire mold assembly with the topping bars 30 in position as in Fig.2 is let stand for an appropriate period for setting of concrete.Thereafter the topping bars are lifted ott and the mold opened,releasing the entire gang of completed tongue-and-grooved concreteplanks P ready for storage, shipment and use. It is found that theresultant longitudinal top tongues t, with reference to the moldingposition, are in all respects equal or superior to those as heretoforeformed by recessing at the bottoms of the mold cavities, while theplanks as a whole are materially improved as to accuracy of dimensionand particularly thickness and as to uniform evenness of the side faceswhich are to be presented horizontally in the subsequent use position asllooring, roofing and such purposes. This improved regularity andaccuracy of dimensions is largely attributable to the use of the toppingbars 30 and their rigidifying function with reference to the spacerplates which are thereby retained throughout the molding and settingprocess in accurate planar presentation.

1t will be understood that my invention, as to means, is not limited tothe exemplary embodiment herein illustrated or described, and I setforth its scope in my following claim.

Iclaim:

Tongue-and-groove concrete plank molding equipment comprising aseparable mold including a bottom wall, opposite longitudinal side wallsand opposite end Walls, longitudinal separator plates definingindividual plank cavities, metallic reinforcement elements in eachcavity and laterally spanning between and positively spacing theadjacent separator plates thereof to dimension the mold cavities forreceiving plank-forming material to encase said elements, the bottom andone end wall hav- 5 ing groove-forming ribs centrally of each cavity andthe other end wall having corresponding tongue-forming recesses, and aplurality of topping bars, one for each separator plate and side wall,said bars centrally longitudinally slotted at the under faces forpositive inte locked seating on the top edges of the respectivelongitudinal plates, each said topping bar having a width to overlielateral marginal portions of the two plank cavities at opposite sides ofthe given plate on which it is seated so as to deline between theproximate vertical longitudinai sid-f: faces of adjacent topping bars acentral longitudinal upwardly open top tongue-forming channel for eachplank cavity, each topping bar being centrally positively supported by aseparator plate and havingv the ange portions at each side thereofcooperating with two meid cavities spaced by the supporting plate, theside faces of the topping bars being inclined toward the respectivesupporting plates to afford a trapezoidal crosssectional shape for thetongue-forming channels between the bars so as to correspondingly taperthe plank top tongues to be molded therein.

References Cited in the file of this patent UNTED STATES PATENTS 824,563Millet June 26, 1906 870,588 Rogers Nov. 12, 1907 941,287 Sullivan Nov.23, 1909 942,092 May Dec. 7, 1909 1,115,618 Tomlinson Nov. 3, 19141,276,264 Porter et al Aug, 20, 1918 1,864,773 Stanford June 28, 19322,270,541 Martin Jan. 20, 1942 2,560,781 Schaaf July 17, 1951 FOREIGNPATENTS 665,719 France Sept. 23, 1929

